The present invention relates to electronic data printers and more particularly to method and means for controlling the printing operation in accordance with the changes in the set of type characters used for printing.
There are a wide variety of printers shown in the prior art. There are slow printers such as those that print a single character at a time and high speed printers commonly referred to as line printers, as well as printers that print a partial line of characters at a time. Such printers have an ability to store in a memory the signals representing characters to be printed or recorded on a record medium. Input intelligence for each character desired to be printed is placed in storage in the memory and is used to select from a complete set of type characters for each print position the one desired to be operated for printing at that position. Reference may be made to U.S. Pat Nos. 3,314,360 dated Apr. 18, 1967; 3,366,045 dated Jan. 30, 1968; 2,874,634 dated Feb. 24, 1959; 2,936,704 dated May 17, 1960; 3,099,206 dated July 30, 1963 and 3,803,558 dated Apr. 9, 1974 which are representative of some of the art prior to Applicants' invention.
In such prior art printers use is made of fixed sets of type characters. Thus, in a particular chain or belt printer arrangement the fixed sets of type characters would be presented to a line on a record medium for purposes of printing. In certain applications the restriction to a fixed number of characters in a set may be an undesirable constraint. For example, for a given size belt or chain it may be desirable to modify the number of sets of type characters in order to obtain certain flexibility of printer application. For example, by increasing the number of sets associated with any type carrier by reducing the number of type characters in any set, the access time to type characters or fingers is reduced and hence the printing rate can be increased. It is common to accommodate a change in the number of sets of type characters in any particular printer configuration by exchanging the logic circuit boards employed in controlling printing, for example, by replacing circuit boards. This approach is time consuming, expensive and troublesome. It would be desirable to be able to modify the printing operation of a printer automatically in response to such a change in the number of sets of type characters presented for printing. This would enable the exchange of type carriers, such as belts, chains, drums, etc., without the necessity of changing or adjusting the print control logic circuits.
Accordingly, one object of the invention is to provide an improved apparatus for modifying the printing process being carried out by a printing system in accordance with changes in the number of type characters employed in a set or font of characters for the printing operation.
Another object of this invention is to provide an automatic method and apparatus for controlling printing operation in response to changes in the number of type characters employed in a set for printing.
Another object of this invention is to provide an improved method and apparatus for conveniently changing the printing speed of an electronic printer by an exchange of type carriers.
Another object of this invention is to provide an improved method and apparatus for detecting a change in the number of type characters associated with a set of such characters employed in a printing operation.
Another object of this invention is to provide an an improved method and apparatus for detecting a change in the number of type characters in the sets employed in a printing operation and for modifying the printing process to accommodate such change.
Another object of this invention is to provide an improved recording method and arrangement.
In accordance with one embodiment of the invention a printing arrangement is provided for printing character signals available from a source in character serial form comprising means for producing a respective column signal for each input character signal to indicate the column in which such character signal is to be printed. Type finger or type character signals are provided, indicative of the passage of each of a plurality of type fingers arranged in a plurality of identical sets of type fingers on a common carrier through the various column positions as the type fingers are moved in succession through the various column positions along a line of print. Means are provided for algebraically combining the column signals with the finger signals to provide sum signals. In order to accommodate automatically to a change in the number of type fingers included in the sets or fonts carried by the carrier, means are provided to sense type finger passage to identify the number of type fingers carried per set by the carrier. Finally, means are provided for modifying the sum signals in response to the identical number of type fingers per set such that when the modified sum signals are compared with the character signals to produce control signals for controlling the printing, the proper type characters corresponding to the input character signals are operated at the appropriate column positions to effect printing.